Piezoelectric actuators are transducers that convert electrical energy into a mechanical displacement or stress using a piezoelectric effect. Piezoelectric elements possess good responsiveness and conversion efficiency when converting electrical energy to mechanical energy. Recently, various types of piezoelectric actuators, which use piezoelectric elements and their piezoelectric effects, have been developed. Moreover, these piezoelectric actuators have been implemented in products such as piezoelectric buzzers, inkjet buzzers, inkjet heads of printers, ultrasonic motors, and microelectromechanical systems (MEMS).